When boarding for a back to back cruise before Christmas the female employee who was assisting us was confused on handling a back to back cruise. She had quiet a bit of difficulty during our check in. When I recieved the bill for the credit card I had submitted for our Sign and Sail accounts she inerrantly charged a percentage amount to the card that I was told should have merely been a hold amount on the card. I was told a "hold" on a credit card was not uncommon but should never have been charged to the card. Both Sign and Sail accounts from both sailings were charged to the card and were correct but the hold amount charged is a false charge and yet I cannot get any response from Carnival other than a reference number. I have found out that they are not a member of the Better Business Bureau in Florida and that quiet often money matters with Carnival are their last concern. What do you recommend? I have filed paperwork with my credit card to attest the charges. The charge in error is more than my cruise cost!

If I'm understanding you correctly, the % amt was actually charged to your credit card? This amount was actually on your credit card bill? This should be a fairly easy matter for your credit card company to handle. . They should be able to clear this up within 30 days and you should not be charged any interest for these outstanding charges.
Hope this helps.